2
我得到這個異常：LazyInitializationException中
javax.el.ELException: Error reading 'id' on type com.example.model.Article_$$_javassist_2
...
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:149)
org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:195)
org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185)
com.example.model.Article_$$_javassist_2.getId(Article_$$_javassist_2.java)
...
這裏是我的代碼：
@Entity
@Table(name = "tbl_articles")
public class Article implements Comparable<Article>, Serializable
{
private static final long serialVersionUID = 1L;
@Id
@Column(nullable = false)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
// some other fields
@ManyToMany(cascade = { CascadeType.ALL })
@JoinTable(name = "tbl_articles_categories",
joinColumns = { @JoinColumn(name = "article_id") },
inverseJoinColumns = { @JoinColumn(name = "category_id") })
@ForeignKey(name = "tbl_articles_categories_fkey_article",
inverseName = "tbl_articles_categories_fkey_category")
private Set<Category> categories = new HashSet<Category>();
@ManyToMany(cascade = { CascadeType.ALL })
@JoinTable(name = "tbl_articles_tags",
joinColumns = { @JoinColumn(name = "article_id") },
inverseJoinColumns = { @JoinColumn(name = "tag_id") })
@ForeignKey(name = "tbl_articles_tags_fkey_article",
inverseName = "tbl_articles_tags_fkey_tag")
private Set<Tag> tags = new HashSet<Tag>();
// getters and setters
}
public abstract class BaseService<E, D extends BaseDAO<E>>
{
protected D dao;
public BaseService()
{
}
protected D getDao()
{
return dao;
}
@Autowired
protected void setDAO(D dao)
{
this.dao = dao;
}
@Transactional
public E get(int id)
{
return dao.get(id);
}
}
@Service
public class ArticleService extends BaseService<Article, ArticleDAO>
{
public ArticleService()
{
setDAO(dao);
}
}
public abstract class BaseDAO<E>
{
public abstract E get(int id);
}
@Repository
public class ArticleDAO extends BaseDAO<Article>
{
@Autowired
private SessionFactory sessionFactory;
@Override
public Article get(int id)
{
return (Article) sessionFactory.getCurrentSession().load(Article.class, id);
}
}
在我的控制器現在，我用它來獲取特定的文章：
@RequestMapping("/{id}/{title}.html")
public String article(@PathVariable("id") Integer id, Map<String, Object> map)
{
map.put("article", articleService.get(id));
return "article";
}
我正在使用我的JSP，就像這樣：
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib prefix="slg" uri="http://github.com/slugify" %>
<article>
<c:url value="/blog/${article.id}/${slg:slugify(article.title)}.html" var="articleUrl" />
<h2><a href="${articleUrl}">${article.title}</a></h2>
<span><fmt:formatDate value="${article.creationDate}" pattern="E, dd MMM yyyy" /></span>
<p>
${article.text}
</p>
</article>
這裏是我的Hibernate配置，以及：
# Properties file with Hibernate Settings.
#-------------------------------------------------------------------------------
# Common Settings
hibernate.generate_statistics=false
#hibernate.hbm2ddl.auto=update
hibernate.show_sql=false
#-------------------------------------------------------------------------------
# DB specific Settings
# Property that determines which Hibernate dialect to use
hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
我做錯了嗎？
UPDATE
調試sessionFactory.getCurrentSession()結果：
DEBUG : com.example.model.ArticleDAO - SessionImpl(PersistenceContext[entityKeys=[],collectionKeys=[]];ActionQueue[insertions=[] updates=[] deletions=[] collectionCreations=[] collectionRemovals=[] collectionUpdates=[] unresolvedInsertDependencies=UnresolvedEntityInsertActions[]])
我加入一些全局變量，這也許導致錯誤？在我的控制器中有一個方法：
@ModelAttribute
public void addGlobalObjects(Map<String, Object> map)
{
map.put("section", "blog");
SortedMap<Category, Integer> categories = new TreeMap<Category, Integer>();
for (Category category : categoryService.list())
{
categories.put(category, articleService.size(category));
}
Calendar cal = Calendar.getInstance();
cal.set(Calendar.DAY_OF_MONTH, 1);
cal.add(Calendar.MONTH, ARCHIVE_MONTHS * -1);
SortedMap<Date, Integer> archive = new TreeMap<Date, Integer>();
for (int i = 0; i < ARCHIVE_MONTHS; ++i)
{
cal.add(Calendar.MONTH, 1);
archive.put(cal.getTime(), articleService.size(cal));
}
SortedMap<Tag, Integer> tags = new TreeMap<Tag, Integer>();
for (Tag tag : tagService.list())
{
tags.put(tag, articleService.size(tag));
}
map.put("categories", categories);
map.put("archive", archive);
map.put("tags", tags);
map.put("categoriesSize", categoryService.size());
map.put("tagsSize", tagService.size());
map.put("date", new Date());
}
對於更新的文章實體請參閱上文。
UPDATE2
渴望獲取沒有解決的問題 - 仍然是相同的異常：
@ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.ALL })
最後我得到重複的文章是什麼我不需要......
UPDATE3
嘗試Hibernate.initialize()我得到這個異常：
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.LazyInitializationException: could not initialize proxy - no Session
UPDATE4
我這樣改變了我的get方法：
@Override
public Article get(int id)
{
// return (Article) sessionFactory.getCurrentSession().load(Article.class, id);
return (Article) sessionFactory.getCurrentSession().createCriteria(Article.class).add(Restrictions.eq("id", id)).uniqueResult();
}
這不是一個解決方案，但我不能處理這個問題我會暫時使用。
我已經嘗試過這一點（如前所述here）沒有成功（從Error reading 'id' on type ...到Error reading 'title' on type ...改變了ELException - 也許我用錯了？）：
@Override
public Article get(int id)
{
Article ret = (Article) sessionFactory.getCurrentSession().load(Article.class, id);
sessionFactory.getCurrentSession().update(ret);
return ret;
}
仍然需要一個解決方案！
謝謝您的回答，我已經更新了我的問題。 – dtrunk 2012-07-30 10:28:01
更新我的回答 – 2012-07-30 19:47:57
查看** UPDATE2 ** – dtrunk 2012-07-31 13:57:53